1. Field of the Invention
This invention relates to a method and apparatus for scaling a line pattern to fit an actual line and, more particularly, to a method and apparatus for use in a computer graphics system in which pixel images are generated for display by a raster scan device.
2. Background of the Invention
Applications relating to computer-aided design or computer-aided manufacturing (or CAD/CAM applications, as they usually collectively termed) must render lines in accordance with accepted conventions and standards of appearance. The ANSI Standard Y14.2M-1979 (Line Conventions and Lettering) is one such standard that defines rules for appearance and rendering of lines.
CAD/CAM applications often handle styled line types, in which lines are drawn as one or more recurring line patterns rather than as continuous lines. Lines may, for example, consist of repeating patterns of spaced dashes or of dots alternating with dashes to represent hidden lines, moved positions and the like. It is desirable to be able to render actual lines as an integral number of patterns, rather than with a portion of the pattern truncated.
Brown et al. U.S. Pat. No. 4,677,573, assigned to the owner of this application, discloses hardware for generating styled lines in a computer graphics system. While the disclosed system allows the high-speed generation of styled lines, it does not provide for scaling a line pattern to fit a particular line length.